According to comScore, Bing's growth has continued through the second full week of its launch.

Further analysis using sites like Compete.com and statCounter.com show that Google's search share also increased, which is leading some to say that Microsoft is not progressing in its competition with Google. What most people forget, though, is that Microsoft is not (yet) competing with Google. Companies primarily compete with adversaries who are close to them in market share. For Bing that means Ask.com (fourth place, behind Microsoft) and Yahoo (second place, ahead of Microsoft).

Looking at the traffic numbers being reported, note that both Ask and Yahoo saw declines of about 1% each. So Bing is successfully taking market share from its primary competitors. That's the real story to watch. Whether Bing eventually can make a play to challenge Google for the market lead is a story for another day, but not until (or unless) Bing overtakes Yahoo.

Why should PPC marketers keep following this story? I'll answer that with another question. What is your PPC budget allocation across the major search engines? As Bing's market share changes from week to week, are you nimble enough to make corresponding allocation changes to your budgets? If not, you might be doing a disservice to your brands or your clients' brands.